Arrangement for the vibration - isolating suspension of an electric motor

ABSTRACT

An arrangement for the vibration-isolating or vibration-damping suspension of an electric motor in particular a fan motor, in a fan housing having a non-rotating motor-supporting element connected to a support part at least on one side via an integral elastic element. The elastic element consisting of three sections lying axially one behind another, in precise terms of a support connecting section connected to the support part in a torsion-resistant manner, of a motor connecting section connected to the supporting element in a torsion-resistant manner, and also of elastically deformable intermediate section arranged between the two connecting sections.

This application is a continuation of Ser. No. 09/056,423 filed Apr.7,1998, U.S. Pat. No. 6,107,706.

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates to an arrangement for thevibration-isolating or vibration-damped suspension of an electric motor,in particular to a fan motor in a fan housing. A non-rotatingmotor-supporting element is connected to a support part on at least oneside via an integral elastic element. In this case, the supportingelement is, in particular, designed as an elongated supporting spindle.

A fan equipped with an arrangement of this type is disclosed in U.S.Pat. No. 2,830, 752. In this case, the supporting spindle engages witheach of its two ends directly, in a torsion-resistant manner, into arubber block which, for its part, is mounted in a torsion-resistantmanner on a star-like support part. The intention thereby is to prevent,on the one hand, the supporting spindle from becoming distorted and, onthe other hand, to dampen vibrations between the supporting spindle andthe fan housing.

Similar arrangements are disclosed in DE 41 21 927 Al and German Patent1 175 785. Rubber-elastic elements are likewise provided in both casesfor mounting the motor.

Many applications have the disadvantage, especially when starting theelectric motor, but also in the event of rapid changes in rotationalspeed, that reaction torques are produced. These torques initially beingtransmitted to the supporting spindle due to the consistently very rigidconnection between the motor or its stator and the supporting element orthe supporting spindle. This results in each case in the supportingspindle executing a slight, jerky rotational movement. Using the knownrubber elements, it has been demonstrated that these jerky rotationalmovements of the supporting spindle are disadvantageously transmitted tothe particular support part and hence also to the housing. The result isa disturbing development of noise which is audible as a slight“clicking”. Especially in applications which make use of motors having aplurality of rotational speed stages, this being the case, for example,in fan motors in exhaust hoods. “Clicking” of this type is audible withevery change in rotational speed. If the motor or the fan is used inrelatively large-volume appliances having relatively thin side walls,this noise, owing to structure-borne sound transmission, is clearlyperceptible and therefore extremely disturbing.

The present invention is based on the object of providing a genericarrangement for the suspension of a motor, with which the development ofdisturbing noises is effectively reduced.

This is achieved in accordance with the invention in that the elasticelement consists of three sections lying axially one behind another.These sections include a support connecting section connected to thesupport part in a torsion-resistant manner, a motor connecting sectionconnected to the motor supporting element in a torsion-resistant manner,and also of an elastically deformable intermediate section arrangedbetween the two connecting sections.

The concept “in a torsion-resistant manner” is to be understood here, inconnection with the invention, as meaning that a relative distortion ofthe parts connected to one another is eliminated, i.e. there is asafeguard against distortion. To this end, the elastic element ispreferably connected to the supporting element and/or to the supportpart via plug-in connections which are positive in the direction ofrotation of the motor and thereby prevent relative distortions. Thisalso makes it possible for the individual parts to be installed in aparticularly simple manner simply by plugging them together.

The elastic element according to the invention leads to substantialadvantages owing to the special intermediate section. The intermediatesection is primarily responsible for the isolating and dampingproperties of the elastic element, it being advantageously capable oftwisting elastically when reaction torques occur. At the same time, theproperties with regard to isolating or damping vibrations and reactiontorques can advantageously be influenced (set) by the selection ofmaterial and/or dimensioning of the length and/or cross section of theintermediate section within a wide range. For instance, the torsionalrigidity is increased by enlarging the cross section of the intermediatesection, and an axial extension of this section results in a reductionin the torsional rigidity. The jerky rotational movements of thesupporting element or the supporting spindle which occur in the event ofrapid changes in rotational speed and, in particular, when starting themotor are compensated for and isolated or damped in such a manner, bymeans of elastic distortions made possible according to the invention,in particular in the region of the intermediate section, thattransmission to the support part is virtually ruled out. As a result,disturbing (clicking) noises are reliably avoided.

The following advantages, in particular, can be achieved by theinvention:

1) High spring stiffness in the axial and in the radial directions. Inthe case of use for the suspension of a fan motor in a fan housing, thefan wheel is thereby reliably prevented from grazing against thehousing.

2) Low torsional rigidity and, at the same time, a virtually linear downto a digressive spring characteristic. Good vibration isolation alsofrom oscillation torques being superposed on the motor torque.

3) Simple installation preferably without screw connections, i.e. simplyby plugging together resulting in a very cost-affective production.

4) Avoiding of vulcanized metal-elastomer connections.

5) Advantageously little influence of, in particular axial, dimensionaltolerances of the individual parts of the arrangement according to theinvention on the torsional rigidity, and hence on the basic function ofthe vibration and torsion isolation, since the torsional rigidity of theelastic element is virtually independent of the degree of axialdeformation.

Further advantageous refining features of the invention are included inthe subclaims and in the description which follows.

The invention will be explained in more detail below with reference to apreferred exemplary embodiment which is illustrated in the attacheddrawing. In this case, the use in the case of a centrifugal blower isshown by way of example.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a side view (in the direction of a rotational axis) of acentrifugal blower which is fitted with a motor suspension according tothe invention;

FIG. 2 shows an axial section corresponding to the section line II—II inFIG. 1;

FIG. 3 shows a side view of an elastic element according to theinvention (individual part III according to FIG. 2);

FIG. 4 shows an axial end view in the direction of arrow IV according toFIG. 3;

FIG. 5 shows a view of the other end in the direction of arrow Vaccording to FIG. 3;

FIG. 6 shows an axial section in the plane VI—VI according to FIG. 5;

FIG. 7 shows an enlarged representation of an axial section of anindividual part (indicated in FIG. 2 by VII) of the arrangementaccording to the invention,

FIG. 8 shows a plan view of this individual part in the arrow directionVIII according to FIG. 7;

FIG. 9 shows a side view of an end of the motor supporting spindle; and

FIG. 10 shows an axial end view of the supporting spindle in thedirection of arrow X according to FIG. 9.

In the various figures of the drawing identical parts are alwaysprovided with the same reference numerals and, as a rule, are thereforeonly described once in each case.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The preferred example of use which is illustrated is concerned withsuspending an electric motor 1 as a fan motor in a fan housing 2 in amanner such that it is isolated or damped with respect to vibrations. Inthis example, the electric motor 1 is designed as an external rotormotor, a stator 4 being secured on a fixed, i.e. non-rotating,supporting spindle 6. An external rotor 8 which surrounds the stator 4is mounted rotatively on the supporting spindle 6 via a pivot bearing,the external rotor 8 bearing a fan wheel 10. The example of use which isillustrated is concerned with a centrifugal blower taking in air oneither side.

According to FIG. 2, the supporting spindle 6 is connected to a supportpart 14 at least by one of its ends but preferably by both ends in anessentially identical manner (but mirror-inverted) via a respectivesingle-part elastic element 12. Each support part 14 is, for its part,secured in a fixed location on the housing 2.

As emerges from FIG. 2 in conjunction with FIGS. 3 to 6, provision ismade according to the invention for the, or each, elastic element 12 toconsist of three sections lying axially one behind another, in preciseterms of a support connecting section 16 connected to the support part14 in a torsion-resistant manner, of a motor connecting section 18connected to the supporting spindle 6 in a torsion-resistant manner, andalso of an intermediate section 20 which is arranged between theconnecting sections 16, 18 and can advantageously be twistedelastically. In this case, the elastic element 12 is preferablyconnected to the supporting spindle 6, and also to the support part 14,via simple plug-in connections, it being essential, however, for theseplug-in connections to effect a positive engagement in the direction ofrotation of the motor 1 and thereby to prevent relative distortions.

The motor connecting section 18 is preferably connected indirectly tothe supporting spindle 6 via an additional hub part 22—cf. in thisrespect also FIGS. 7 and 8. For this purpose, on the one hand thesupporting spindle 6 is inserted by one end-side plug-in section 24(illustrated in FIGS. 9 and 10) positively and thereby in atorsion-resistant manner into a plug-in opening 26 in the hub part 22.This plug-in procedure is illustrated by a dashed line between FIGS. 9and 7. On the other hand, the motor connecting section 18 has a crosssection which deviates from the circular form and is, in particular,polygonal, and is seated positively and thereby in a torsion-resistantmanner in a socket 28, of matching cross section, of the hub part 22. Inthis manner, the supporting spindle 6 is hence connected to the elasticelement 12 in a torsion-resistant manner. In the preferred exemplaryembodiment which is illustrated—cf. In particular FIGS. 5 and 8—themotor connecting section 18 and, accordingly, also the socket 28 of thehub part 22 in each case have a regularly polygonal, to be precisepreferably a hexagonal, cross section. However, the invention is in noway limited to this.

As emerges from FIGS. 7 and 8, the hub part 22 is preferably designed inthe manner of a cap with a base 30 which extends perpendicularly orradially with respect to the supporting spindle 6, a circumferentialwall 32 which determines the cross section of the socket 28 (and hencealso the cross section of the motor connecting section 18) and pointsaxially in the direction of the support part 14, and with an inner,central annular extension 34 which has or surrounds the plug-in opening26 for the supporting spindle 6 or the end-side plug-in section 24thereof. According to FIG. 6, the motor connecting section 18 of theelastic element 12 has a central socket recess 36 for the axial annularextension 34 of the hub part 22 and the plug-in section 24, which isseated positively therein, of the supporting spindle 6. The cap-like hubpart 22 can be plugged positively onto the motor connecting section 18proceeding from FIG. 7 in the direction of the dashed arrow leading toFIG. 6.

For the positive, torsion-resistant connection between the plug-insection 24 of the supporting spindle 6 and the hub part 22, provision ispreferably made, in the example shown, for the plug-in section 24 tohave an axial slot 38 preferably running diametrically (FIGS. 9 and 10),there being formed within the plug-in opening 26 in the hub part 22(cf—FIG. 8) at least one radial projection 40 which engages positivelyinto the axial slot 38 of the plug-in section 24. The axial slot 38determines, by means of its axial length, the insertion depth into theplug-in opening 26, i.e. the slot end brings about a limitation oninsertion. The plug-in section 24 preferably has a circular outer crosssection, and the plug-in opening 26 has an essentially likewisematching, circular inner cross section (apart from the preferably twodiametrically opposite, radial projections 40). This preferredconnection between the supporting spindle 6 and the hub part 22advantageously also enables a reliable connection which is non-positivein the axial direction and is virtually free of circumferential play tobe achieved.

As an alternative to the preferred embodiment, it is likewise possiblefor the plug-in section 24 and the plug-in opening 26 to be designedsuch that they have an outer cross section contour which deviates fromthe circular form, for example is polygonal, in order to be able toobtain a plug-in connection which is secure against torsion.

The hub part 22 is preferably made of metal, die-cast zinc beingparticularly suitable (preferably an alloy Z410 according to DIN1734/1). This opens up the advantageous option of using the hub part 22for conducting away heat from the motor. For this purpose, it isexpedient for the hub part 22 to be fitted with external cooling ribs 42(FIGS. 7 and 8). These advantageously enable the heat produced in themotor 1 to be effectively conducted away to the outside air by the heatfirst being transmitted from the stator 4 to the supporting spindle6—which likewise is expediently made of metal—and from there to the hubpart 22, the hub part 22, assisted by the cooling ribs 42, theneffectively releasing the heat to the outside air. As emerges from FIGS.7 and 8, the cooling ribs 42 are preferably integrally formedapproximately radially on the circumferential wall 32 of the cap-likehub part 22. When used as a centrifugal blower, the hub part 22 isadvantageously situated in the intake region and the air taken intherefore circulates intensively around it, resulting in good cooling.

As far as the support connecting section 16 of the elastic element 12 isconcerned, said section, which likewise has a cross section deviatingfrom the circular form, is seated positively and hence in atorsion-resistant manner in an appropriately matched socket 44 of thesupport part 14 (cf. FIG. 2). Each support part 14 is designed—in amanner known per se—as a supporting star having, in particular, threesupporting arms 46 arranged in a radially symmetrical manner. At thesame time, in its central region the socket 44 for the supportconnecting section 16 is formed having, in particular, an essentiallytriangular cross section. The support connecting section 16 thereforelikewise has a matching, approximately triangular cross section; cf.,for this purpose, FIG. 4 in particular. Each support part 14 isexpediently designed as a sheet-metal stamped part having bent overwalls 48 which bound the socket 44 (FIG. 2).

The intermediate section 20 of the elastic element 12 preferably has anessentially circular cross section. According to FIG. 3, this crosssection is expediently tapered with respect to the cross sections of thetwo adjacent connecting sections 16, 18. The isolating and dampingproperties can be influenced by dimensioning the length and the crosssection of the intermediate section 20 and also by selecting a specific,elastomeric material, as has already been explained at the beginning.

Moreover, it is advantageous if the elastic element 12 has an axiallycontinuous, central lead-through opening 50 for motor connecting leads52 (cf. FIG. 2). With regard to this, the supporting spindle 6 has, atleast at one end, an axial, central guide channel 54 for the connectingleads 52. This guide channel 54 preferably leads approximately radiallyor obliquely outwards into a connecting region of the electric motor 1,as is shown in FIG. 2. The support part 14 arranged on the connectingside likewise has a central lead-through opening 56 for the connectingleads 52 (cf. FIG. 1). It is advantageous if the elastic element 12 hasan annular extension 58, engaging axially into this lead-through opening56 in the support part 14, for protecting the connecting leads 52against mechanical damage by the hole rim of the lead-through opening 56(cf—also FIG. 9 - 3, 4 and 6 for this purpose). This means that thelead-through opening 56 is practically cushioned by the annularextension 58 of the elastic element 12.

In addition to the preferably provided positive plug-in connections,provision may be made for the elastic element 12 also to be bonded tothe hub part 22 and/or to the support part 12. This supplementary bondmay, for example, be achieved by introducing silicone or the like beforeplugging the parts together.

The elastic element 12 is preferably composed of an elastomeric materialhaving a hardness approximately in the region of 50-60 Shore A. EPDM(abbreviation in accordance with DIN 7728, Part I forethylene/propylene-diene terpolymers or ethylene-propylene elastomers)is particularly suitable. However, the refinement or function accordingto the invention also allows elements composed of a material having ahigher Shore hardness and, as a result, the aging resistance andmechanical strength thereof is improved.

In the preferred exemplary embodiment, in which both ends of thesupporting spindle 6 are similarly mounted via a respective elasticelement 12, the positive plug-in connections are advantageously solelyfixed in the axial direction by axial deformation of the support parts14 by the support parts 14 being secured on the housing 2 at a defineddistance from one another. In this case, it has been advantageouslydemonstrated that axial deformation of the elastic elements 12 hasvirtually no influence on the torsional rigidity.

The invention is not limited to the exemplary embodiments which havebeen represented and described; rather it also includes all embodimentswhich act in the same manner as the invention. Thus, the invention is inprinciple also suitable for internal rotor motors, the elastic elements12 being positioned between support parts integrally formed on the endshields and an outer mount. The shaft of the internal rotor motor can heguided outwards on one side or on both sides through the axiallycontinuous, central lead-through opening 40 in the elastic element 12.

Furthermore, the invention is not at this point limited to thecombination of features defined in claim 1 rather it can also be definedby any other combination desired of certain features of all of theindividual features which have been disclosed as a whole. This meansthat in principle virtually any individual feature of claim 1 can beomitted or replaced by at least one individual feature disclosed atanother location in the application. In this respect, claim 1 is merelyto he understood as a first formulating attempt for an invention.

What is claimed is:
 1. An arrangement for the torque and vibrationisolating or damping suspension of an electric motor comprising anon-rotating motor-supporting element having a longitudinal axis beingconnected to a support part at least on one side of said motor via anintegral elastic element, wherein said elastic element includes threesections positioned adjacently along said longitudinal axis, anon-circular support connecting section connected to said support partin a torsion-resistant manner, a non-circular motor connecting sectionconnected to said supporting element in a torsion-resistant manner, andan elastically deformable intermediate section arranged between saidconnecting sections which undergoes torsional deflection between saidconnecting sections, wherein a hub part is interposed between saidelastic element and said supporting element such that said supportingelement is not directly connected to said motor connecting section ofsaid elastic element.
 2. The arrangement as claimed in claim 1, whereinsaid supporting element is inserted by a end-side plug-in section in atorsion-resistant manner into a plug-in opening in said hub part.
 3. Thearrangement as claimed in claim 1, wherein said motor connecting sectionis polygonally-shaped and is seated in a torsion-resistant manner in asocket of said hub part, said socket having a cross-sectioncorresponding to said shape of said motor connecting section.
 4. Thearrangement as claimed in claim 3, wherein said motor connecting sectionand said socket of said hub part have a regular polygonally-shapedcross-section.
 5. The arrangement as claimed in claim 1, wherein saidhub part includes a cap with a base extending perpendicularly to saidsupporting spindle, a circumferential wall pointing axially in thedirection of said support part, and an inner central annular extensionsurrounding said plug-in opening for said supporting element.
 6. Thearrangement as claimed in claim 5, wherein said motor connecting sectionof said elastic element has a central socket recess for said annularextension of said hub part and said plug-in section of said supportingelement which is seated therein.
 7. A suspension structure for mountingan electric motor in a housing, said structure comprising: a motorsupport having a longitudinal axis; a one-piece, elastically deformabledamping element; and a hub; said motor support being connected to saidhousing on at least one side of said motor by said hub and said dampingelement; said hub being located intermediate said motor support and saiddamping element such that said motor support does not directly engagesaid damping element; said damping element comprising: a first sectionengaging said housing; a second section engaging said hub; and a thirdsection located intermediate said first section and said second sectionoperable to deflect in response to a load applied to said dampingelement; said first, second, and third sections being arranged in thedirection of said longitudinal axis.